Guest geology by David Middleton

Recent analyses of data collected by ESA’s Venus Express spacecraft indicates that some of the lava flows on Venus might be very young…

RESEARCH ARTICLE PLANETARY SCIENCE
Present-day volcanism on Venus as evidenced from weathering rates of olivine

Justin Filiberto¹,*, David Trang², Allan H. Treiman¹ and Martha S. Gilmore³

Abstract

At least some of Venus’ lava flows are thought to be <2.5 million years old based on visible to near-infrared (VNIR) emissivity measured by the Venus Express spacecraft. However, the exact ages of these flows are poorly constrained because the rate at which olivine alters at Venus surface conditions, and how that alteration affects VNIR spectra, remains unknown. We obtained VNIR reflectance spectra of natural olivine that was altered and oxidized in the laboratory. We show that olivine becomes coated, within days, with alteration products, primarily hematite (Fe₂O₃). With increasing alteration, the VNIR 1000-nm absorption, characteristic of olivine, also weakens within days. Our results indicate that lava flows lacking VNIR features due to hematite are no more than several years old. Therefore, Venus is volcanically active now.

Filiberto et al., 2019 (Full text available)

ESA had previously reported evidence of recent volcanic activity on Venus.

The “Near‐Infrared Mapping Spectrometer (NIMS) on board the Galileo spacecraft” may have granitic rocks on Venus, indicating that it once had active active tectonics, continents and oceans. Could Venus still be tectonically active? Maybe.

Back in the 1990’s the Magellan spacecraft also provided some spectacular radar images of Venusian volcanoes and lava flows.

Volcanoes Elsewhere in our Solar System

Earth and the Jovian moon Io are the only two planets or planetary bodies in the solar system known to have active volcanoes. Oddly enough, Io’s volcanoes are in the wrong place, according to models.

Scientists to Io: Your Volcanoes Are in the Wrong Place

Jupiter’s moon Io is the most volcanically active world in the Solar System, with hundreds of volcanoes, some erupting lava fountains up to 250 miles high. However, concentrations of volcanic activity are significantly displaced from where they are expected to be based on models that predict how the moon’s interior is heated, according to NASA and European Space Agency researchers.

[…]

NASA

Venus would make it three.

Mars and the Moon were also volcanically active in the geologic past. Remote sensing data and the geomorphology of Io, Venus and Mars indicate that the lava flows are primarily of a basaltic nature. The Moon’s maria lava flows have been confirmed to be composed primarily of basalt. Lunar basalt is mineralogically similar to Earth’s, although there is a significant and diagnostic geochemical difference. Lunar rocks and regolith plot along a distinct FeO_T vs. Al₂O₃ trend. In the image below, I plotted mare basalt samples collected by the Apollo 11 & 12 missions along with a wide variety of terrestrial basalt samples.

Lunar basalt is enriched in in iron oxide and depleted in aluminum oxide, relative to similar rocks on Earth.

Cryovolcanoes

Neptune’s moon Triton and Saturn’s moon Enceladus appear to have cryovolcanoes. These features are composed of ice and erupt water vapor.

References

Filiberto, J., Trang, D., Treiman, A.H., Gilmore, M., 2020. Present-day volcanism on Venus as evidenced from weathering rates of olivine. Science Advances, 6: eaax7445.

Hashimoto, G. L., Roos‐Serote, M., Sugita, S., Gilmore, M. S., Kamp, L. W., Carlson, R. W., and Baines, K. H. ( 2008), Felsic highland crust on Venus suggested by Galileo Near‐Infrared Mapping Spectrometer data, J. Geophys. Res., 113, E00B24, doi:10.1029/2008JE003134.